1. Field of the Invention
The invention relates generally to method and apparatus for obtaining ice core specimens from a block or sheet of ice and relates particularly to improved ice coring auger apparatus adapted to efficiently cut an ice core specimen with a reduced- in-diameter "neck" portion which facilitates clear breakage of the specimen from the ice block or sheet.
2. Description of the Prior Art
Ice core specimens are obtained from ice sheets or ice blocks for purposes of analysis. In order for this analysis to yield valid results, it is necessary that the specimen have its structural integrity. Due to the fact that ice is a relatively weak and brittle material, ice core specimens are often damaged or effectively destroyed during the cutting process or during the process of breaking off the specimen from the remainder of the ice block or sheet after an initially successful machining with an ice coring auger.
Arduous conditions such as are imposed by artic weather or by extremely low temperatures in a laboratory facility where ice coring is normally undertaken often contribute to the difficulties involved in obtaining ice core specimens of requisite quality. While ice coring auger structures have been available for the cutting or "machining" of an ice core within a block or sheet of ice, a successfully machined finished core must be still retrieved from the body of ice from which the core has been cut. Often, successfully machined ice core specimens are destroyed or damaged during attempts to remove the specimen from the ice at its "root" since it is difficult to assure that breakage of the specimen from the ice will be confined to the root of the brittle core specimen. Prior ice coring augers have thus failed to overcome those problems previously encountered in obtaining ice core specimens of high "quality".
Examples of prior ice core cutting and coring mechanisms include U.S. Pat. Nos. 2,880,968 to Titeca and 4,539,750 to Jarvi et al. In these prior patents, cutter elements are provided which function in the primary cutting of an ice core. However, as is the situation throughout the prior art, the mechanisms of Titeca and Jarvi et al do not provide structure which facilitates the retrieval of an ice core specimen from an ice block or sheet once the core specimen has been successfully machined. Accordingly, the prior art has not provided methodology or apparatus suitable for cutting an ice core specimen from an ice block or sheet and which functions to facilitate recovery or retrieval of the core from the ice with minimal damage to the specimen.